The present invention relates to a self-powered emergency descent system for elevator systems. More particularly, the present invention pertains to the use of the kinetic energy of an elevator cab descending due to gravitational forces to generate electrical energy to regulate the speed of descent to the ground level or any other assigned floor located below the elevator cab.
Elevator systems and controls for such systems are known in the art. Such systems and controls use a wide variety of designs to achieve numerous objectives, and the basic principle of balancing an elevator cab against a counterweight via a cable and sheave assembly driven by a motor is known to those skilled in the art.
For years, building designers and code authorities have recognized the necessity of emergency power in buildings to ensure that elevator cabs descend to the ground level in the event of power loss due to a building fire or any other reason. Without an independent source of power for the elevator system, any power outage could compromise the safety of passengers in the elevator cab.
Various approaches have been described in the prior art for providing emergency power for elevator systems. Many of these devices have been subject to a range of difficulties and disadvantages. For example, batteries sufficiently powerful to drive an elevator or multiple elevators typically are large, expensive, require invertors, and require extensive maintenance. Similarly, fossil fuel driven generators are large, expensive, and require extensive maintenance and testing. In many buildings, finding a desirable location for the installation of emergency back up systems with large footprints represents a significant engineering challenge. Moreover, most elevator systems currently require building power distribution systems to provide transfer switches and emergency feeders for elevators and main distribution emergency switchboards and emergency generators sufficiently large to cover elevator loads, all of which result in additional costs and inefficiencies.
Thus, it would be advantageous to have an elevator system that during a power outage or any other occasion when needed accomplishes the controlled descent of the elevator cab without a battery or fossil fuel based generator to drive the elevator motor, but rather accomplishes the initial descent of the elevator cab due to gravitational forces and the heaviness of the elevator cab relative to an attached counterweight, and which then converts kinetic energy of the descending elevator cab into electrical energy used to control the speed of descent of the elevator cab.
The invention provides for an elevator system, detachable counterweight, and an elevator system upgrade kit that provides a self-generating emergency power source for elevators by converting the kinetic energy of the elevator cab descending due to gravitational forces and the heaviness of the cab relative to the attached counterweight, into electrical energy used to regulate the speed of descent to the ground level or any other assigned floor located below the elevator cab. The elevator system includes either a generator or a motor operating in generator mode that is driven by a descending elevator cab. The elevator system accomplishes the initial descent of the elevator cab during a power outage, or otherwise when needed, by either (1) using a counterweight that is sufficiently lighter than the elevator cab to cause the cab to descend due to its relative heaviness, or (2) due to a locking system joining a detachable counterweight to a permanent counterweight whereby power loss or interruption causes the unlocking of the detachable counterweight from the permanent counterweight and thereby resulting in the descent of the elevator cab due to its heaviness relative to the permanent counterweight. The elevator upgrade kit operates in a similar way, but includes the modification of the counterweights and generators or motors in existing elevator systems. In elevator systems in which a braking system is activated by an outside power loss, an elevator controller with a small battery back-up directs the brakes to release after a preset time and remain released while the elevator cab accomplishes its descent. The kinetic energy represented by the raised elevator cab is the source of emergency power for the elevator system. When gravitational forces cause the elevator cab to descend, an attached generator or motor in generator mode driven by the descending elevator cab converts the kinetic energy into electrical energy to control the descent of the elevator cab.
It is therefore an object of the invention to provide an improved elevator system and an elevator upgrade kit so designed that the kinetic energy of the descending elevator cab can be used to generate its own emergency power for a regulated speed of descent to the ground level or any other floor located below the elevator cab.
It is another object of the present invention to provide an improved elevator system and an elevator upgrade kit that provides an emergency power source for elevators more reliable than conventional elevator emergency power sources.
It is still another object of the present invention to provide an improved elevator system and elevator upgrade kit that provides an independent reliable emergency power source to drive an elevator cab down with a controlled speed of descent to evacuate passengers to a safe area during a fire or power outage.
It is still another object of the present invention to provide an improved elevator system and elevator upgrade kit that provides an emergency power source for elevators that eliminates the need for building power distribution systems to provide transfer switches and emergency feeders for elevators.
It is still another object of the present invention to provide an improved elevator system and elevator upgrade kit that provides an emergency power source for elevators that allows for reductions in the size of main distribution emergency switchboards and emergency generators because those devices no longer would need to cover elevator loads.
It is finally another object of the present invention to provide an improved elevator system and elevator upgrade kit that achieves the efficiencies of a well-balanced counterweight to elevator cab ratio, while allowing for the elevator cab to descend and thereby convert its kinetic energy into electrical energy upon the detachment of the detachable counterweight from the permanent counterweight.
Further advantages and features of the present invention will be apparent from the foregoing specification and claims once considered in connection with the accompanying drawings illustrating the preferred embodiment of the invention.